or at least did. Someone didn't conform to the rules a leader decided to set forth, they were (and in some places still are) killed, no questions asked. The most basic instincts of all is to try to protect your own survival and in the cases of some species, the survival of your offspring. Therefore you insist your children follow those rules, and follow them yourself. Somewhere along the line someone who was able to convince enough people decided (whether they truly believed they were commanded so by god(s) or not) to use "God says so" as they reason. People with some degree of faith do not want to make god angry. Therefore they start to believe that if god(s) don't want them to show the goods, they better not, which made the rules stick even harder.
If modesty were truly part of human nature, wouldn't all cultures share the same sense of modesty? All people would be inclined to cover up the same amount rather than some cultures being fine with pretty much everything hanging out for all to see, while other cultures insist that (women especially) not show any more skin than they can possibly avoid. (What is considered "modest" in Rio de Janero for example, is NOT considered "modest" in dowtown Kabul) |